A "common law system" is a legal system that gives great precedential weight to common law,[2] so that consistent principles applied to similar facts yield similar outcomes.[3] The body of past common law binds judges that make future decisions, just as any other law does, to ensure consistent treatment. In cases where the parties disagree on what the law is, a common law court looks to past precedential decisions of relevant courts. If a similar dispute has been resolved in the past, the court is usually bound to follow the reasoning used in the prior decision (this principle is known as stare decisis). If, however, the court finds that the current dispute is fundamentally distinct from all previous cases (called a "matter of first impression"), judges have the authority and duty to make law by creating precedent.[4] Thereafter, the new decision becomes precedent, and will bind future courts.

In practice, common law systems are considerably more complicated than the simplified system described above. The decisions of a court are binding only in a particular jurisdiction, and even within a given jurisdiction, some courts have more power than others. For example, in most jurisdictions, decisions by appellate courts are binding on lower courts in the same jurisdiction, and on future decisions of the same appellate court, but decisions of lower courts are only non-binding persuasive authority. Interactions between common law, constitutional law, statutory law and regulatory law also give rise to considerable complexity. However, stare decisis, the principle that cases should be decided according to consistent principled rules so that similar facts will yield similar results, lies at the heart of all common law systems.

arising from the traditional and inherent authority of courts to define what the law is, even in the absence of an underlying statute or regulation. Examples include most criminal law and procedural law before the 20th century, and even today, most contract law and the law of torts.

(b) interstitial common law

court decisions that analyze, interpret and determine the fine boundaries and distinctions in law promulgated by other bodies. This body of common law (connotation 1), sometimes called "interstitial common law," includes judicial interpretation of the Constitution, of legislative statutes, and of agency regulations, and the law application of law to specific facts.[13]

2. Common law legal systems as opposed to civil law legal systems[edit]

Connotation 2 differentiates "common law" jurisdictions and legal systems from "civil law" or "code" jurisdictions.[13] Common law (connotation 2) systems place great weight on court decisions, which are considered "law" with the same force of law as statutes—for nearly a millennium, common law (connotation 2) courts have had the authority to make law where no legislative statute exists, and statutes mean what courts interpret them to mean. By contrast, in civil law jurisdictions (the legal tradition that prevails, or is combined with common law, in Europe and most non-Islamic, non-common law countries), courts lack authority to act where there is no statute, and judicial precedent is given less interpretive weight (which means that a judge deciding a given case has more freedom to interpret the text of a statute independently, and less predictably), and scholarly literature is given more. For example, the Napoleonic code expressly forbade French judges to pronounce general principles of law.[14]

Connotation 3 differentiates "common law" (or just "law") from "equity".[11][12] Before 1873, England had two parallel court systems: courts of "law" that could only award money damages and recognized only the legal owner of property, and courts of "equity" (courts of chancery) that could issue injunctive relief (that is, a court order to a party to do something, give something to someone, or stop doing something) and recognized trusts of property. This split propagated to many of the colonies, including the United States (see "Reception Statutes", below). For most purposes, most jurisdictions, including the U.S. federal system and most states, have merged the two courts.[15][16] Additionally, even before the separate courts were merged, most courts were permitted to apply both law (connotation 3) and equity, though under potentially different procedural law. Nonetheless, the historical distinction between "law" (in connotation 3) and "equity" remains important today when the case involves issues such as the following:

in the United States, determining whether the Seventh Amendment's right to a jury trial applies (a determination of a fact necessary to resolution of a "common law" claim)[17] or whether the issue will be decided by a judge (issues of what the law is, and all issues relating to equity).

the standard of review and degree of deference given by an appellate tribunal to the decision of the lower tribunal under review (issues of law are reviewed de novo, that is, "as if new" from scratch by the appellate tribunal, while most issues of equity are reviewed for "abuse of discretion," that is, with great deference to the tribunal below).

In addition, there are several historical uses of the term that provide some background as to its meaning.

In one archaic usage, "common law" refers to the pre-Christian system of law, imported by the Saxons to England, and dating to before the Norman conquest, and before there was any consistent law to be applied.[18][19] This definition is found or alluded to in some internet dictionaries.[20]

The English Court of Common Pleas dealt with lawsuits in which the Monarch had no interest, i.e., between commoners.

Additionally, from at least the 11th century and continuing for several centuries after that, there were several different circuits in the royal court system, served by itinerant judges who would travel from town to town dispensing the King's justice. The term "common law" was used to describe the law held in common between the circuits and the different stops in each circuit. The more widely a particular law was recognized, the more weight it held, whereas purely local customs were generally subordinate to law recognized in a plurality of jurisdictions.

These definitions are archaic, their relevance having dissipated with the development of the English legal system over the centuries, but they do explain the origin of the term as used today.

In a common law jurisdiction several stages of research and analysis are required to determine "what the law is" in a given situation. First, one must ascertain the facts. Then, one must locate any relevant statutes and cases. Then one must extract the principles, analogies and statements by various courts of what they consider important to determine how the next court is likely to rule on the facts of the present case. Later decisions, and decisions of higher courts or legislatures carry more weight than earlier cases and those of lower courts.[22] Finally, one integrates all the lines drawn and reasons given, and determines "what the law is". Then, one applies that law to the facts.

The common law evolves to meet changing social needs and improved understanding[edit]

Justice Holmes cautioned that “the proper derivation of general principles in both common and constitutional law ... arise gradually, in the emergence of a consensus from a multitude of particularized prior decisions.”[23]Justice Cardozo noted the “common law does not work from pre-established truths of universal and inflexible validity to conclusions derived from them deductively,” but “[i]ts method is inductive, and it draws its generalizations from particulars.”[24]

The common law (connotation 1) is more malleable than statutory law. First, common law courts are not absolutely bound by precedent, but can (when extraordinarily good reason is shown) reinterpret and revise the law, without legislative intervention, to adapt to new trends in political, legal and social philosophy. Second, the common law (connotation 1) evolves through a series of gradual steps, that gradually works out all the details, so that over a decade or more, the law can change substantially but without a sharp break, thereby reducing disruptive effects.[25] In contrast to common law incrementalism, the legislative process is very difficult to get started, as legislatures tend to delay action until a situation is totally intolerable.[citation needed] For these reasons, legislative changes tend to be large, jarring and disruptive (sometimes positively, sometimes negatively, and sometimes with unintended consequences).

One example of the gradual change that typifies evolution of the common law (connotation 1) is the gradual change in liability for negligence. For example, the traditional common law rule through most of the 19th century was that a plaintiff could not recover for a defendant's negligent production or distribution of a harmful instrumentality unless the two were in privity of contract. Thus, only the immediate purchaser could recover for a product defect, and if a part was built up out of parts from parts manufacturers, the ultimate buyer could not recover for injury caused by a defect in the part. In an 1842 English case, Winterbottom v. Wright,[26] the postal service had contracted with Wright to maintain its coaches. Winterbottom was a driver for the post. When the coach failed and injured Winterbottom, he sued Wright. The Winterbottom court recognized that there would be "absurd and outrageous consequences" if an injured person could sue any person peripherally involved, and knew it had to draw a line somewhere, a limit on the causal connection between the negligent conduct and the injury. The court looked to the contractual relationships, and held that liability would only flow as far as the person in immediate contract ("privity") with the negligent party.

A first exception to this rule arose in an 1852 case by New York's highest court, Thomas v. Winchester,[27] which held that mislabeling a poison as an innocuous herb, and then selling the mislabeled poison through a dealer who would be expected to resell it, put "human life in imminent danger." Thomas used this as a reason to create an exception to the "privity" rule. In, 1909, New York held in Statler v. Ray Mfg. Co.[28] that a coffee urn manufacturer was liable to a person injured when the urn exploded, because the urn "was of such a character inherently that, when applied to the purposes for which it was designed, it was liable to become a source of great danger to many people if not carefully and properly constructed."

Yet the privity rule survived. In Cadillac Motor Car Co. v. Johnson,[29] (decided in 1915 by the federal appeals court for New York and several neighboring states), the court held that a car owner could not recover for injuries from a defective wheel, when the automobile owner had a contract only with the automobile dealer and not with the manufacturer, even though there was "no question that the wheel was made of dead and ‘dozy‘ wood, quite insufficient for its purposes." The Cadillac court was willing to acknowledge that the case law supported exceptions for "an article dangerous in its nature or likely to become so in the course of the ordinary usage to be contemplated by the vendor." However, held the Cadillac court, "one who manufactures articles dangerous only if defectively made, or installed, e.g., tables, chairs, pictures or mirrors hung on the walls, carriages, automobiles, and so on, is not liable to third parties for injuries caused by them, except in case of willful injury or fraud,"

Finally, in the famous case of MacPherson v. Buick Motor Co.,[30] in 1916, Judge Benjamin Cardozo for New York's highest court pulled a broader principle out of these predecessor cases. The facts were almost identical to Cadillac a year earlier: a wheel from a wheel manufacturer was sold to Buick, to a dealer, to MacPherson, and the wheel failed, injuring MacPherson. Judge Cardozo held:

It may be that Statler v. Ray Mfg. Co. have extended the rule of Thomas v. Winchester. If so, this court is committed to the extension. The defendant argues that things imminently dangerous to life are poisons, explosives, deadly weapons—things whose normal function it is to injure or destroy. But whatever the rule in Thomas v. Winchester may once have been, it has no longer that restricted meaning. A scaffold (Devlin v. Smith, supra) is not inherently a destructive instrument. It becomes destructive only if imperfectly constructed. A large coffee urn (Statler v. Ray Mfg. Co., supra) may have within itself, if negligently made, the potency of danger, yet no one thinks of it as an implement whose normal function is destruction. What is true of the coffee urn is equally true of bottles of aerated water (Torgeson v. Schultz, 192 N. Y. 156). We have mentioned only cases in this court. But the rule has received a like extension in our courts of intermediate appeal. In Burke v. Ireland (26 App. Div. 487), in an opinion by CULLEN, J., it was applied to a builder who constructed a defective building; in Kahner v. Otis Elevator Co. (96 App. Div. 169) to the manufacturer of an elevator; in Davies v. Pelham Hod Elevating Co. (65 Hun, 573; affirmed in this court without opinion, 146 N. Y. 363) to a contractor who furnished a defective rope with knowledge of the purpose for which the rope was to be used. We are not required at this time either to approve or to disapprove the application of the rule that was made in these cases. It is enough that they help to characterize the trend of judicial thought.

We hold, then, that the principle of Thomas v. Winchester is not limited to poisons, explosives, and things of like nature, to things which in their normal operation are implements of destruction. If the nature of a thing is such that it is reasonably certain to place life and limb in peril when negligently made, it is then a thing of danger. Its nature gives warning of the consequences to be expected. If to the element of danger there is added knowledge that the thing will be used by persons other than the purchaser, and used without new tests then, irrespective of contract, the manufacturer of this thing of danger is under a duty to make it carefully. ... There must be knowledge of a danger, not merely possible, but probable.

Cardozo's new "rule" exists in no prior case, but is inferrable as a synthesis of the "thing of danger" principle stated in them, merely extending it to "foreseeable danger" even if "the purposes for which it was designed" were not themselves "a source of great danger." MacPherson takes some care to present itself as foreseeable progression, not a wild departure. Cardozo continues to adhere to the original principle of Winterbottom, that "absurd and outrageous consequences" must be avoided, and he does so by drawing a new line in the last sentence quoted above: "There must be knowledge of a danger, not merely possible, but probable." But while adhering to the underlying principle that some boundary is necessary, MacPherson overruled the prior common law by rendering the formerly dominant factor in the boundary, that is, the privity formality arising out of a contractual relationship between persons, totally irrelevant. Rather, the most important factor in the boundary would be the nature of the thing sold and the foreseeable uses that downstream purchasers would make of the thing.

This illustrates two crucial principles that are often not well understood by non-lawyers. (a) The common law evolves, this evolution is in the hands of judges, and judges have "made law" for hundreds of years. (b) The reasons given for a decision are often more important in the long run than the outcome in a particular case. This is the reason that judicial opinions are usually quite long, and give rationales and policies that can be balanced with judgment in future cases, rather than the bright-line rules usually embodied in statutes.

In almost all areas of the law (even those where there is a statutory framework, such as contracts for the sale of goods,[32] or the criminal law),[33] legislature-enacted statutes generally give only terse statements of general principle, and the fine boundaries and definitions exist only in the interstitial common law (connotation 1(b)). To find out what the precise law is that applies to a particular set of facts, one has to locate precedential decisions on the topic, and reason from those decisions by analogy. To consider but one example, the First Amendment to the United States Constitution states "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof"—but interpretation (that is, determining the fine boundaries, and resolving the tension between the "establishment" and "free exercise" clauses) of each of the important terms was delegated by Article III of the Constitution to the judicial branch,[34] so that the current legal boundaries of the Constitutional text can only be determined by consulting interstitial common law (connotation 1(b)).[35]

In common law jurisdictions (connotation 2), legislatures operate under the assumption that statutes will be interpreted against the backdrop of the pre-existing common law (connotation 1) and custom. For example, in most U.S. states, the criminal statutes are primarily codification of pre-existing common law. (Codification is the process of enacting a statute that collects and restates pre-existing law in a single document—when that pre-existing law is common law, the common law remains relevant to the interpretation of these statutes.) In reliance on this assumption, modern statutes often leave a number of terms and fine distinctions unstated—for example, a statute might be very brief, leaving the precise definition of terms unstated, under the assumption that these fine distinctions will be inherited from pre-existing common law. (For this reason, many modern American law schools teach the common law of crime as it stood in England in 1789, because that centuries-old English common law is a necessary foundation to interpreting modern criminal statutes.)

With the transition from English law, which had common law crimes, to the new legal system under the U.S. Constitution, which prohibited ex post facto laws at both the federal and state level, the question was raised whether there could be common law crimes in the United States. It was settled in the case of United States v. Hudson and Goodwin, 11 U.S.32 (1812), which decided that federal courts had no jurisdiction to define new common law crimes, and that there must always be a (constitutional) statute defining the offense and the penalty for it.

Still, many states retain selected common law crimes. For example, in Virginia, the definition of the conduct that constitutes the crime of robbery exists only in the common law, and the robbery statute only sets the punishment.[36]Virginia Code section 1-200 establishes the continued existence and vitality of common law principles and provides that "The common law of England, insofar as it is not repugnant to the principles of the Bill of Rights and Constitution of this Commonwealth, shall continue in full force within the same, and be the rule of decision, except as altered by the General Assembly."

By contrast to statutory codification of common law, some statutes displace common law, for example to create a new cause of action that did not exist in the common law, or to legislatively overrule the common law. An example is the tort of wrongful death, which allows certain persons, usually a spouse, child or estate, to sue for damages on behalf of the deceased. There is no such tort in English common law; thus, any jurisdiction that lacks a wrongful death statute will not allow a lawsuit for the wrongful death of a loved one. Where a wrongful death statute exists, the compensation or other remedy available is limited to the remedy specified in the statute (typically, an upper limit on the amount of damages). Courts generally interpret statutes that create new causes of action narrowly—that is, limited to their precise terms—because the courts generally recognize the legislature as being supreme in deciding the reach of judge-made law unless such statute should violate some "second order" constitutional law provision (cf. judicial activism).

Where a tort is rooted in common law (connotation 1(a)), all traditionally recognized damages for that tort may be sued for, whether or not there is mention of those damages in the current statutory law. For instance, a person who sustains bodily injury through the negligence of another may sue for medical costs, pain, suffering, loss of earnings or earning capacity, mental and/or emotional distress, loss of quality of life, disfigurement and more. These damages need not be set forth in statute as they already exist in the tradition of common law. However, without a wrongful death statute, most of them are extinguished upon death.

In the United States, the power of the federal judiciary to review and invalidate unconstitutional acts of the federal executive branch is stated in the constitution, Article III sections 1 and 2: "The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish. ... The judicial Power shall extend to all Cases, in Law and Equity, arising under this Constitution, the Laws of the United States, and Treaties made, or which shall be made, under their Authority..." The first famous statement of "the judicial power" was Marbury v. Madison, 5 U.S. (1 Cranch) 137 (1803). Later cases interpreted the "judicial power" of Article III to establish the power of federal courts to consider or overturn any action of Congress or of any state that conflicts with the Constitution.

The interactions between decisions of different courts is discussed further in the article on precedent.

The United States federal courts are divided into twelve regional circuits, each with a circuit court of appeals (plus a thirteenth, the Court of Appeals for the Federal Circuit, which hears appeals in patent cases and cases against the federal government, without geographic limitation). Decisions of one circuit court are binding on the district courts within the circuit and on the circuit court itself, but are only persuasive authority on sister circuits. District court decisions are not binding precedent at all, only persuasive.

Most of the U.S. federal courts of appeal have adopted a rule under which, in the event of any conflict in decisions of panels (most of the courts of appeal almost always sit in panels of three), the earlier panel decision is controlling, and a panel decision may only be overruled by the court of appeals sitting en banc (that is, all active judges of the court) or by a higher court.[37] In these courts, the older decision remains controlling when an issue comes up the third time.

Other courts, for example, the Court of Customs and Patent Appeals and the Supreme Court, always sit en banc, and thus the later decision controls. These courts essentially overrule all previous cases in each new case, and older cases survive only to the extent they do not conflict with newer cases. The interpretations of these courts—for example, Supreme Court interpretations of the constitution or federal statutes—are stable only so long as the older interpretation maintains the support of a majority of the court. Older decisions persist through some combination of belief that the old decision is right, and that it is not sufficiently wrong to be overruled.

The reliance on judicial opinion is a strength of common law systems, and is a significant contributor to the robust commercial systems in the United Kingdom and United States. Because there is reasonably precise guidance on almost every issue, parties (especially commercial parties) can predict whether a proposed course of action is likely to be lawful or unlawful, and have some assurance of consistency. As Justice Brandeis famously expressed it, “in most matters it is more important that the applicable rule of law be settled than that it be settled right.”[39] This ability to predict gives more freedom to come close to the boundaries of the law.[40] For example, many commercial contracts are more economically efficient, and create greater wealth, because the parties know ahead of time that the proposed arrangement, though perhaps close to the line, is almost certainly legal. Newspapers, taxpayer-funded entities with some religious affiliation, and political parties can obtain fairly clear guidance on the boundaries within which their freedom of expression rights apply.

In contrast, in non-common-law countries, and jurisdictions with very weak respect for precedent (example, the U.S. Patent Office), fine questions of law are redetermined anew each time they arise, making consistency and prediction more difficult, and procedures far more protracted than necessary because parties cannot rely on written statements of law as reliable guides. In jurisdictions that do not have a strong allegiance to a large body of precedent, parties have less a priori guidance and must often leave a bigger "safety margin" of unexploited opportunities, and final determinations are reached only after far larger expenditures on legal fees by the parties.

This is the reason for the frequent choice of the law of the State of New York in commercial contracts, even when neither entity has extensive contacts with New York—and remarkably often even when neither party has contacts with the United States.[41] Commercial contracts almost always include a "choice of law clause" to reduce uncertainty. Somewhat surprisingly, contracts throughout the world (for example, contracts involving parties in Japan, France and Germany, and from most of the other states of the United States) often choose the law of New York, even where the relationship of the parties and transaction to New York is quite attenuated. Because of its history as the United States' commercial center, New York common law has a depth and predictability not (yet) available in any other jurisdictions of the United States. Similarly, American corporations are often formed under Delaware corporate law, and American contracts relating to corporate law issues (merger and acquisitions of companies, rights of shareholders, and so on.) include a Delaware choice of law clause, because of the deep body of law in Delaware on these issues.[42] On the other hand, some other jurisdictions have sufficiently developed bodies of law so that parties have no real motivation to choose the law of a foreign jurisdiction (for example, England and Wales, and the state of California), but not yet so fully developed that parties with no relationship to the jurisdiction choose that law.[43] Outside the United States, parties that are in different jurisdictions from each other often choose the law of England and Wales, particularly when the parties are each in former British colonies and members of the Commonwealth. The common theme in all cases is that commercial parties seek predictability and simplicity in their contractual relations, and frequently choose the law of a common law jurisdiction with a well-developed body of common law to achieve that result.

Likewise, for litigation of commercial disputes arising out of unpredictable torts (as opposed to the prospective choice of law clauses in contracts discussed in the previous paragraph), certain jurisdictions attract an unusually high fraction of cases, because of the predictability afforded by the depth of decided cases. For example, London is considered the pre-eminent centre for litigation of admiralty cases.[44]

This is not to say that common law is better in every situation. For example, civil law can be clearer than case law when the legislature has had the foresight and diligence to address the precise set of facts applicable to a particular situation. For that reason, civil law statutes tend to be somewhat more detailed than statutes written by common law legislatures—but, conversely, that tends to make the statute more difficult to read (the United States tax code is an example).[45] Nonetheless, as a practical matter, no civil law legislature can ever address the full spectrum of factual possibilities in the breadth, depth and detail of the case law of the common law courts of even a smaller jurisdiction, and that deeper, more complete body of law provides additional predictability that promotes commerce.

The term "common law" originally derives from the 1150s and 1160s, when Henry II of England established the secular English tribunals. The "common law" was the law that emerged as "common" throughout the realm (as distinct from the various legal codes that preceded it, such as Mercian law, the Danelaw and the law of Wessex)[46] as the king's judges followed each other's decisions to create a unified common law throughout England. The doctrine of precedent developed during the 12th and 13th centuries,[47] as the collective judicial decisions that were based in tradition, custom and precedent.[48]

In the late 800s, Alfred the Great assembled the Doom book (not to be confused with the more-famous Domesday Book from 200 years later), which collected the existing laws of Kent, Wessex, and Mercia, and attempted to blend in the Mosaic code, Christian principles, and Germanic customs dating as far as the fifth century.[49]

In 1154, Henry II became the first Plantagenet king. Among many achievements, Henry institutionalized common law by creating a unified system of law "common" to the country through incorporating and elevating local custom to the national, ending local control and peculiarities, eliminating arbitrary remedies and reinstating a jury system—citizens sworn on oath to investigate reliable criminal accusations and civil claims. The jury reached its verdict through evaluating common local knowledge, not necessarily through the presentation of evidence, a distinguishing factor from today's civil and criminal court systems.

Henry II developed the practice of sending judges from his own central court to hear the various disputes throughout the country. His judges would resolve disputes on an ad hoc basis according to what they interpreted the customs to be. The king's judges would then return to London and often discuss their cases and the decisions they made with the other judges. These decisions would be recorded and filed. In time, a rule, known as stare decisis (also commonly known as precedent) developed, whereby a judge would be bound to follow the decision of an earlier judge; he was required to adopt the earlier judge's interpretation of the law and apply the same principles promulgated by that earlier judge if the two cases had similar facts to one another. Once judges began to regard each other's decisions to be binding precedent, the pre-Norman system of local customs and law varying in each locality was replaced by a system that was (at least in theory, though not always in practice) common throughout the whole country, hence the name "common law."

Henry II's creation of a powerful and unified court system, which curbed somewhat the power of canonical (church) courts, brought him (and England) into conflict with the church, most famously with Thomas Becket, the Archbishop of Canterbury. Eventually, Becket was murdered inside Canterbury Cathedral by four knights who believed themselves to be acting on Henry's behalf. Whether Henry actually intended to bring about the assassination of Becket is debatable, but there is no question that at the time of the murder, the two men were embroiled in a bitter dispute regarding the power of Royal Courts to exercise jurisdiction over former clergymen. The murder of the Archbishop gave rise to a wave of popular outrage against the King. Henry was forced to repeal the disputed laws and to abandon his efforts to hold church members accountable for secular crimes (see also Constitutions of Clarendon).

Judge-made common law operated as the primary source of law for several hundred years, before Parliament acquired legislative powers to create statutory law. It is important to understand that common law is the older and more traditional source of law, and legislative power is simply a layer applied on top of the older common law foundation. Since the 12th century, courts have had parallel and co-equal authority to make law[51]—"legislating from the bench" is a traditional and essential function of courts, which was carried over into the U.S. system as an essential component of the "judicial power" specified by Article III of the U.S. constitution.[52] Justice Oliver Wendell Holmes, Jr. observed in 1917 that "judges do and must legislate."[53] There are legitimate debates on how the powers of courts and legislatures should be balanced. However, a view that courts lack law-making power is historically inaccurate and constitutionally unsupportable.

The term "common law" (connotation 2) is often used as a contrast to Roman-derived "civil law", and the fundamental processes and forms of reasoning in the two are quite different. Nonetheless, there has been considerable cross-fertilization of ideas, while the two traditions and sets of foundational principles remain distinct.

By the time of the rediscovery of the Roman law in Europe in the 12th and 13th centuries, the common law had already developed far enough to prevent a Roman law reception as it occurred on the continent.[54] However, the first common law scholars, most notably Glanvill and Bracton, as well as the early royal common law judges, had been well accustomed with Roman law. Often, they were clerics trained in the Roman canon law.[55] One of the first and throughout its history one of the most significant treatises of the common law, Bracton’s De Legibus et Consuetudinibus Angliae (On the Laws and Customs of England), was heavily influenced by the division of the law in Justinian’s Institutes.[56] The impact Roman law had decreased sharply after the age of Bracton, but the Roman divisions of actions into in rem (typically, actions against a thing or property for the purpose of gaining title to that property; must be filed in a court where the property is located) and in personam (typically, actions directed against a person; these can affect a person's rights and, since a person often owns things, his property too) used by Bracton had a lasting effect and laid the groundwork for a return of Roman law structural concepts in the 18th and 19th centuries. Signs of this can be found in Blackstone’s Commentaries on the Laws of England,[57] and Roman law ideas regained importance with the revival of academic law schools in the 19th century.[58] As a result, today, the main systematic divisions of the law into property, contract, and tort (and to some extent unjust enrichment) can be found in the civil law as well as in the common law.[59]

Propagation of the common law to the colonies and Commonwealth by reception statutes[edit]

A reception statute is a statutory law adopted as a former British colony becomes independent, by which the new nation adopts (i.e. receives) pre-independence English law, to the extent not explicitly rejected by the legislative body or constitution of the new nation. Reception statutes generally consider the English common law dating prior to independence, and the precedents originating from it, as the default law, because of the importance of using an extensive and predictable body of law to govern the conduct of citizens and businesses in a new state. All U.S. states, with the partial exception of Louisiana, have either implemented reception statutes or adopted the common law by judicial opinion.[60]

Other examples of reception statutes in the United States, the states of the U.S., Canada and its provinces, and Hong Kong, are discussed in the reception statute article.

Decline of Latin maxims, and adding flexibility to stare decisis[edit]

Well into the 19th century, ancient maxims played a large role in common law adjudication. Many of these maxims had originated in Roman Law, migrated to England before the introduction of Christianity to the British Isles, and were typically stated in Latin even in English decisions. Many examples are familiar in everyday speech even today, "One cannot be a judge in one's own cause" (see Dr. Bonham's Case), rights are reciprocal to obligations, and the like. Judicial decisions and treatises of the 17th and 18th centuries, such at those of Lord Chief Justice Edward Coke, presented the common law as a collection of such maxims. See also Thomas Jefferson's letter to Thomas Cooper.

Reliance on old maxims and rigid adherence to precedent, no matter how old or ill-considered, was under full attack by the late 19th century. Oliver Wendell Holmes, Jr. in his famous article, "The Path of the Law",[61] commented, "It is revolting to have no better reason for a rule of law than that so it was laid down in the time of Henry IV. It is still more revolting if the grounds upon which it was laid down have vanished long since, and the rule simply persists from blind imitation of the past." Justice Holmes noted that study of maxims might be sufficient for "the man of the present," but "the man of the future is the man of statistics and the master of economics." In an 1880 lecture at Harvard, he wrote:

The life of the law has not been logic; it has been experience. The felt necessities of the time, the prevalent moral and political theories, intuitions of public policy, avowed or unconscious, even the prejudices which judges share with their fellow men, have had a good deal more to do than the syllogism in determining the rules by which men should be governed. The law embodies the story of a nation's development through many centuries, and it cannot be dealt with as if it contained only the axioms and corollaries of a book of mathematics.

In the early 20th century, Louis Brandeis, later appointed to the United States Supreme Court, became noted for his use of policy-driving facts and economics in his briefs, and extensive appendices presenting facts that lead a judge to the advocate's conclusion. By this time, briefs relied more on facts than on Latin maxims.

Reliance on old maxims is now deprecated.[62] Common law decisions today reflect both precedent and policy judgment drawn from economics, the social sciences, business, decisions of foreign courts, and the like. The degree to which these external factors should influence adjudication is the subject of active debate, but that judges do draw of learning from other fields and jurisdictions is a fact of modern legal life.

1870 through 20th century, and the procedural merger of law and equity[edit]

As early as the 15th century, it became the practice that litigants who felt they had been cheated by the common-law system would petition the King in person. For example, they might argue that an award of damages (at common law (connotation 3)) was not sufficient redress for a trespasser occupying their land, and instead request that the trespasser be evicted. From this developed the system of equity, administered by the Lord Chancellor, in the courts of chancery. By their nature, equity and law were frequently in conflict and litigation would frequently continue for years as one court countermanded the other,[63] even though it was established by the 17th century that equity should prevail. A famous example is the fictional case of Jarndyce v. Jarndyce in Bleak House, by Charles Dickens.[64]

In the United States, parallel systems of law (providing money damages, with cases heard by a jury upon either party's request) and equity (fashioning a remedy to fit the situation, including injunctive relief, heard by a judge) survived well into the 20th century. The United States federal courts procedurally separated law and equity: the same judges could hear either kind of case, but a given case could only pursue causes in law or in equity, and the two kinds of cases proceeded under different procedural rules. This became problematic when a given case required both money damages and injunctive relief. In 1937, the new Federal Rules of Civil Procedure combined law and equity into one form of action, the "civil action." Fed.R.Civ.P. 2. The distinction survives to the extent that issues that were "common law (connotation 3)" as of 1791 (the date of adoption of the Seventh Amendment) are still subject to the right of either party to request a jury, and "equity" issues are decided by a judge.[65]

For centuries, through the 19th century, the common law recognized only specific forms of action, and required very careful drafting of the opening pleading (called a writ) to slot into one of them: Debt, Detinue, Covenant, Special Assumpsit, General Assumpsit, Trespass, Trover, Replevin, Case (or Trespass on the Case), and Ejectment.[66] To initiate a lawsuit, a pleading had to be drafted to meet myriad technical requirements: correctly categorizing the case into the correct legal pigeonhole (pleading in the alternative was not permitted), and using specific "magic words" encrusted over the centuries. Under the old common law pleading standards, a suit by a pro se ("for oneself," without a lawyer) party was all but impossible, and there was often considerable procedural jousting at the outset of a case over minor wording issues.

One of the major reforms of the late 19th century and early 20th century was the abolition of common law pleading requirements.[67] A plaintiff can initiate a case by giving the defendant "a short and plain statement" of facts that constitute an alleged wrong. This reform moved the attention of courts from technical scrutiny of words to a more rational consideration of the facts, and opened access to justice far more broadly.

Common law systems tend to give more weight to separation of powers between the judicial branch (which promulgates common law (connotation 1)) and the executive branch (which promulgates regulatory law, called "administrative law" in civil law systems). In contrast, civil law systems often allow individual officials to exercise both powers.

In common law systems, a single decided case is binding common law (connotation 1), under the principle of stare decisis. In contrast, in civil law systems, case law only acquires weight when a long series of cases use consistent reasoning, called jurisprudence constante. In civil law systems, individual decisions have only advisory, not binding effect.

Both common law and civil law jurisdictions have formed what they variously call "pure common law" or "general principles of law" to define what the law is in the absence of, or gap in, legislation. In common law systems, judge made law is binding to the same extent as statute or regulation. In civil law systems, case law is advisory, not binding. Civil law lawyers consult case law to obtain their best prediction of how a court will rule, but comparatively, civil law judges are less bound to follow it.

Common law courts usually use an adversarial system, in which two sides present their cases to a neutral judge. In contrast, civil law systems usually use an inquisitorial system in which an examining magistrate serves two roles by developing the evidence and arguments for one side and then the other during the investigation phase.

The examining magistrate then presents the dossier detailing his or her findings to the president of the bench that will adjudicate on the case where it has been decided that a trial shall be conducted. Therefore the president of the bench's view of the case is not neutral and may be biased while conducting the trial after the reading of the dossier. Unlike the common law proceedings, the president of the bench in the inquisitorial system is not merely an umpire and is entitled to directly interview the witnesses or express comments during the trial, as long as he or she does not express his or her view on the guilt of the accused.

The proceeding in the inquisitorial system is essentially by writing. Most of the witnesses would have given evidence in the investigation phase and such evidence will be contained in the dossier under the form of police reports. In the same way, the accused would have already put his or her case at the investigation phase but he or she will be free to change her or his evidence at trial. Whether the accused pleads guilty or not, a trial will be conducted. Unlike the adversarial system, the conviction and sentence to be served (if any) will be released by the trial jury together with the president of the trial bench, following their common deliberation.

There are many exceptions in both directions. For example, most proceedings before U.S. federal and state agencies are inquisitorial in nature, at least the initial stages (e.g., a patent examiner, a social security hearing officer, and so on), even though the law to be applied is developed through common law processes.

Contrasting role of treatises and academic writings in common law and civil law systems[edit]

The role of the legal academy presents a significant "cultural" difference between common law (connotation 2) and civil law jurisdictions.

In common law jurisdictions, legal treatises compile common law decisions and state overarching principles that (in the author's opinion) explain the results of the cases. However, in common law jurisdictions, treatises are not the law, and lawyers and judges tend to use these treatises as only "finding aids" to locate the relevant cases. In common law jurisdictions, scholarly work is seldom cited as authority for what the law is.[68] When common law courts rely on scholarly work, it is almost always only for factual findings, policy justification, or the history and evolution of the law, but the court's legal conclusion is reached through analysis of relevant statutes and common law, seldom scholarly commentary.

In contrast, in civil law jurisdictions, courts give the writings of law professors significant weight, partly because civil law decisions traditionally were very brief, sometimes no more than a paragraph stating who wins and who loses. The rationale had to come from somewhere else: the academy often filled that role. This balance may shift as civil law court decisions move in the direction of common law reasoning.[citation needed]

Scotland is often said to use the civil law system, but it has a unique system that combines elements of an uncodified civil law dating back to the Corpus Juris Civilis with an element of its own common law long predating the Treaty of Union with England in 1707 (see Legal institutions of Scotland in the High Middle Ages), founded on the customary laws of the tribes residing there. Historically, Scots common law differed in that the use of precedents was subject to the courts' seeking to discover the principle that justifies a law rather than searching for an example as a precedent,[69] and principles of natural justice and fairness have always played a role in Scots Law. From the 19th century, the Scottish approach to precedent developed into a stare decisis akin to that already established in England thereby reflecting a narrower, more modern approach to the application of case law in subsequent instances. This is not to say that the substantive rules of the common laws of both countries are the same although in many matters (particularly those of UK-wide interest) they are very similar. Comparable pluralistic (or 'mixed') legal systems operate in Quebec, Louisiana and South Africa.

The state of New York, which also has a civil law history from its Dutch colonial days, also began a codification of its law in the 19th century. The only part of this codification process that was considered complete is known as the Field Code applying to civil procedure. The original colony of New Netherland was settled by the Dutch and the law was also Dutch. When the English captured pre-existing colonies they continued to allow the local settlers to keep their civil law. However, the Dutch settlers revolted against the English and the colony was recaptured by the Dutch. When the English finally regained control of New Netherland they forced, as a punishment unique in the history of the British Empire, the English imposed common law upon all the colonists, including the Dutch. This was problematic, as the patroon system of land holding, based on the feudal system and civil law, continued to operate in the colony until it was abolished in the mid-19th century. The influence of Roman-Dutch law continued in the colony well into the late 19th century. The codification of a law of general obligations shows how remnants of the civil law tradition in New York continued on from the Dutch days.

Under the Louisiana's codified system, the Louisiana Civil Code, private law--that is, substantive law between private sector parties--is based on principles of law from continental Europe, with some common law influences. These principles derive ultimately from Roman law, transmitted through French law and Spanish law, as the state's current territory intersects the area of North America colonized by Spain and by France. Contrary to popular belief, the Louisiana code does not directly derive from the Napoleonic Code, as the latter was enacted in 1804, one year after the Louisiana Purchase. However, the two codes are similar in many respects due to common roots.

The United States federal government (as opposed to the states) has a variant on a common law system. United States federal courts only act as interpreters of statutes and the constitution by elaborating and precisely defining the broad language (connotation 1(b) above), but, unlike state courts, do not act as an independent source of common law (connotation 1(a) above).

Before 1938, the federal courts, like almost all other common law courts, decided the law on any issue where the relevant legislature (either the U.S. Congress or state legislature, depending on the issue), had not acted, by looking to courts in the same system, that is, other federal courts, even on issues of state law, and even where there was no express grant of authority from Congress or the Constitution.

In 1938, the U.S. Supreme Court in Erie Railroad Co. v. Tompkins304 U.S. 64, 78 (1938), overruled earlier precedent,[70] and held "There is no federal general common law," thus confining the federal courts to act only as interpreters of law originating elsewhere. E.g., Texas Industries v. Radcliff, 451 U.S.630 (1981) (without an express grant of statutory authority, federal courts cannot create rules of intuitive justice, for example, a right to contribution from co-conspirators). Post-1938, federal courts deciding issues that arise under state law are required to defer to state court interpretations of state statutes, or reason what a state's highest court would rule if presented with the issue, or to certify the question to the state's highest court for resolution.

Later courts have limited Erie slightly, to create a few situations where United States federal courts are permitted to create federal common law rules without express statutory authority, for example, where a federal rule of decision is necessary to protect uniquely federal interests, such as foreign affairs, or financial instruments issued by the federal government. See, e.g., Clearfield Trust Co. v. United States, 318 U.S.363 (1943) (giving federal courts the authority to fashion common law rules with respect to issues of federal power, in this case negotiable instruments backed by the federal government); see alsoInternational News Service v. Associated Press, 248 U.S. 215 (1918) (creating a cause of action for misappropriation of "hot news" that lacks any statutory grounding); but see National Basketball Association v. Motorola, Inc., 105 F.3d 841, 843–44, 853 (2d Cir. 1997) (noting continued vitality of INS "hot news" tort under New York state law, but leaving open the question of whether it survives under federal law). Except on Constitutional issues, Congress is free to legislatively overrule federal courts' common law.[71]

Most executive branch agencies in the United States federal government have some adjudicatory authority. To greater or lesser extent, agencies honor their own precedent to ensure consistent results. Agency decision making is governed by the Administrative Procedure Act of 1946.

Indian family law is complex, with each religion adhering to its own specific laws. In most states, registering marriages and divorces is not compulsory. There are separate laws governing Hindus, Muslims, Christians, Sikhs and followers of other religions. The exception to this rule is in the state of Goa, where a Portugueseuniform civil code is in place, in which all religions have a common law regarding marriages, divorces and adoption.

Ancient India represented a distinct tradition of law, and had an historically independent school of legal theory and practice. The Arthashastra, dating from 400 BCE and the Manusmriti, from 100 CE, were influential treatises in India, texts that were considered authoritative legal guidance.[73]Manu's central philosophy was tolerance and pluralism, and was cited across Southeast Asia.[74] Early in this period, which finally culminated in the creation of the Gupta Empire, relations with ancient Greece and Rome were not infrequent. The appearance of similar fundamental institutions of international law in various parts of the world show that they are inherent in international society, irrespective of culture and tradition.[75] Inter-State relations in the pre-Islamic period resulted in clear-cut rules of warfare of a high humanitarian standard, in rules of neutrality, of treaty law, of customary law embodied in religious charters, in exchange of embassies of a temporary or semi-permanent character.[76] When India became part of the British Empire, there was a break in tradition, and Hindu and Islamic law were supplanted by the common law.[77] As a result, the present judicial system of the country derives largely from the British system and has little correlation to the institutions of the pre-British era.[78]

Canada has separate federal and provincial legal systems. The division of jurisdiction between the federal and provincial Parliaments is specified in the Canadian constitution.[80]

Each province is considered a separate jurisdiction with respect to common law matters. As such, only the provincial legislature may enact legislation to amend private law. Each has its own procedural law, statutorily created provincial courts and superior trial courts with inherent jurisdiction culminating in the Court of Appeal of the province. This is the highest court in provincial jurisdiction, only subject to the Supreme Court of Canada in terms of appeal of their decisions. All but one of the provinces of Canada use a common law system (the exception being Quebec, which uses a civil law system for issues arising within provincial jurisdiction, such as property ownership and contracts).

Canadian federal statutes must use the terminology of both the common law and civil law for those matters; this is referred to as legislative bijuralism.[81]

Federal Courts operate under a separate system throughout Canada and deal with narrower subject matter than superior courts in provincial jurisdiction. They hear cases reserved for federal jurisdiction by the Canadian constitution, such as immigration, intellectual property, judicial review of federal government decisions, and admiralty. The Federal Court of Appeal is the appellate level court in federal jurisdiction and hears cases in multiple cities, and unlike the United States, the Canadian Federal Court of Appeal is not divided into appellate circuits.[82]

Criminal law is uniform throughout Canada. It is based on the constitution and federal statutory Criminal Code, as interpreted by the Supreme Court of Canada. The administration of justice and enforcement of the criminal code are the responsibilities of the provinces.

Nicaragua's legal system also is a mixture of the English Common Law and the Civil Law.[citation needed] This situation was brought through the influence of British administration of the Eastern half of the country from the mid-17th century until about 1905, the William Walker period from about 1855 through 1857, USA interventions/occupations during the period from 1909 to 1933, the influence of USA institutions during the Somoza family administrations (1933 through 1979) and the considerable importation between 1979 and the present of USA culture and institutions.[citation needed]

Israel has a common law legal system. Its basic principles are inherited from the law of the British Mandate of Palestine and thus resemble those of British and American law, namely: the role of courts in creating the body of law and the authority of the supreme court[83] in reviewing and if necessary overturning legislative and executive decisions, as well as employing the adversarial system. One of the primary reasons that the Israeli constitution remains unwritten is the fear by whatever party holds power that creating a written constitution, combined with the common-law elements, would severely limit the powers of the Knesset (which, following the doctrine of parliamentary sovereignty, holds near-unlimited power).[84]

Roman Dutch Commons law is a bijuridical or mixed system of law similar to the common law system in Scotland and Louisiana. Roman Dutch common law jurisdictions include South Africa, Botswana, Lesotho, Namibia, Swaziland, Sri-Lanka and Zimbabwe. Many of these jurisdictions recognise customary law, and in some, such as South Africa the Constitution requires that the common law be developed in accordance with the Bill of Rights. Roman Dutch common law is a development of Roman Dutch law by courts in the Roman Dutch common law jurisdictions. During the Napoleonic wars the Kingdom of the Netherlands adopted the French code civil in 1809, however the Dutch colonies in the Cape of Good Hope and Sri Lanka, at the time called Ceylon, were seized by the British to prevent them being used as bases by the French Navy. The system was developed by the courts and spread with the expansion of British colonies in Southern Africa. Roman Dutch common law relies on legal principles set out in Roman law sources such as Justinian's Institutes and Digest, and also on the writing of Dutch jurists of the 17th century such as Grotius and Voet. In practice, the majority of decisions rely on recent precedent.

The main alternative to the common law system is the civil law system, which is used in Continental Europe, and most of the rest of the world. The contrast between civil law and common law legal systems has become increasingly blurred, with the growing importance of jurisprudence (similar to case law but not binding) in civil law countries, and the growing importance of statute law and codes in common law countries.

Examples of common law being replaced by statute or codified rule in the United States include criminal law (since 1812, U.S. courts have held that criminal law must be embodied in statute if the public is to have fair notice), commercial law (the Uniform Commercial Code in the early 1960s) and procedure (the Federal Rules of Civil Procedure in the 1930s and the Federal Rules of Evidence in the 1970s). But note that in each case, the statute sets the general principles, but the interstitial common law process (connotation 1(b)) determines the scope and application of the statute.

Lord Chief Justice Edward Coke, a 17th-century English jurist and Member of Parliament, wrote several legal texts that formed the basis for the modern common law, with lawyers in both England and America learning their law from his Institutes and Reports until the end of the 18th century. His works are still cited by common law courts around the world.

In the United States, Restatements of various subject matter areas (Contracts, Torts, Judgments, and so on.), edited by the American Law Institute, collect the common law for the area. The ALI Restatements are often cited by American courts and lawyers for propositions of uncodified common law, and are considered highly persuasive authority, just below binding precedential decisions. The Corpus Juris Secundum is an encyclopedia whose main content is a compendium of the common law and its variations throughout the various state jurisdictions.

Scots common law covers matters including murder and theft, and has sources in custom, in legal writings and previous court decisions. The legal writings used are called Institutional Texts and come mostly from the 17th, 18th and 19th centuries. Examples include Craig, Jus Feudale (1655) and Stair, The Institutions of the Law of Scotland (1681).

^Marbury v. Madison, 5 U.S. 137 (1803) ("It is emphatically the province and duty of the judicial department to say what the law is. Those who apply the rule to particular cases, must of necessity expound and interpret that rule. If two laws conflict with each other, the courts must decide on the operation of each.")

^"In Suits at common law ... the right of trial by jury shall be preserved, and no fact tried by a jury shall be otherwise reexamined in any Court of the United States, than according to the rules of the common law."

^Jefferson, Thomas (February 10, 1814). "Letter to Dr. Thomas Cooper". Retrieved 11 July 2012. Authorities for what is common law may therefore be as well cited, as for any part of the Lex Scripta, and there is no better instance of the necessity of holding the judges and writers to a declaration of their authorities than the present; where we detect them endeavoring to make law where they found none, and to submit us at one stroke to a whole system, no particle of which has its foundation in the common law. For we know that the common law is that system of law which was introduced by the Saxons on their settlement in England, and altered from time to time by proper legislative authority from that time to the date of Magna Carta, which terminates the period of the common law, or lex non scripta, and commences that of the statute law, or Lex Scripta. This settlement took place about the middle of the fifth century. But Christianity was not introduced till the seventh century; the conversion of the first christian king of the Heptarchy having taken place about the year 598, and that of the last about 686. Here, then, was a space of two hundred years, during which the common law was in existence, and Christianity no part of it.

^Jefferson, Thomas (June 5, 1824). "Letter To Major John Cartwright". Retrieved 11 July 2012. I was glad to find in your book a formal contradiction, at length, of the judiciary usurpation of legislative powers; for such the judges have usurped in their repeated decisions, that Christianity is a part of the common law. The proof of the contrary, which you have adduced, is incontrovertible; to wit, that the common law existed while the Anglo-Saxons were yet Pagans, at a time when they had never yet heard the name of Christ pronounced, or knew that such a character had ever existed.

^E.g., Lectric Law Dictionary : That which derives its force and authority from the universal consent and immemorial practice of the people. It is at best obsolete. It is both underinclusive and overinclusive. Lawyers never rely on this definition.

^The beneficial qualities of the common law's incrementalist evolution was most eloquently expressed by the future Lord Mansfield, then Solicitor General Murray, in the case of Omychund v. Barker, who contended that "a statute very seldom can take in all cases; therefore the common law, that works itself pure by rules drawn from the fountain of justice, is for that reason superior to an act of parliament." I Atk. 21, 33, 26 Eng. Rep. 15, 22–23 (Ch. 1744)

^Meister v. Moore, 96 U.S. 76 (1877) ("No doubt a statute may take away a common law right, but there is always a presumption that the legislature has no such intention unless it be plainly expressed.")

^To consider one example, Lemon v. Kurtzman, 403 U.S. 602 (1971), resolves one part of the tension between the "establishment" and "free exercise" clauses of the First Amendment with a three part test: a government-sponsored message violates the Establishment Clause if: (1) it does not have a secular purpose; (2) its principal or primary effect advances or inhibits religion; or (3) it creates an excessive entanglement of the government with religion..

^E.g., South Corp. v. United States, 690 F.2d 1368 (Fed. Cir. 1982) (en banc in relevant part) (explaining order of precedent binding on the United States Court of Appeals for the Federal Circuit); Bonner v. City of Prichard, Alabama, 661 F.2d 1206 (11th Cir. 1981) (en banc) (after the Eleventh Circuit was split off from the Fifth Circuit, adopting precedent of Fifth Circuit as binding until overruled by the Eleventh Circuit en banc: "The [pre-split] Fifth followed the absolute rule that a prior decision of the circuit (panel or en banc) could not be overruled by a panel but only by the court sitting en banc. The Eleventh Circuit decides in this case that it chooses, and will follow, this rule."); Ex parte Holt, 19 USPQ2d 1211, 1214 (Bd. Patent App. & Interf. 1991) (explaining the hierarchy of precedent binding on tribunals of the United States Patent Office).

^Theodore Eisenberg & Geoffrey P. Miller, The Flight to New York: An Empirical Study of Choice of Law and Choice of Forum Clauses in Publicly-Held Companies’ Contracts (2008). New York University Law and Economics Working Papers. Paper 124, http://lsr.nellco.org/nyu_lewp/124 (based on a survey of 2882 contracts, "New York law plays a role for major corporate contracts similar to the role Delaware law plays in the limited setting of corporate governance disputes. ... New York’s dominance is striking. It is the choice of law in approximately 46 percent of contracts," and if merger contracts excluded, over half)

^Eisenberg & Miller at 19–20 (Delaware is chosen in about 15% of contracts, "Delaware dominates for one type of contract—[merger] trust agreements. ... The dominance of Delaware for this specialized type of contract is apparently due to the advantages and flexibility which Delaware’s business trust statute.")

^Eisenberg & Miller at 19, only about 5% of commercial contracts designate California choice of law, where nearly 50% designate New York.

^Osley, Richard (2008-11-23). "London becomes litigation capital of the world". The Independent (London).. London is also forum for many defamation cases, because U.K. law is more plaintiff-friendly—in the United States, the First Amendment protection for freedom of the press allows for statements concerning public figures of questionable veracity, where in the U.K., those same statements support a judgment for libel.

^Winston Chruchill, A History of the English Speaking Peoples, Chapter 13, The English Common Law

^seeOliver Wendell Holmes, Jr., The Common Law, Lecture I, sec. 2, "In Massachusetts today...there are some (rules) which can only be understood by reference to the infancy of procedure among the German tribes."

^William Burnham, Introduction to the Law and Legal System of the United States, 4th ed. (St. Paul, Thomson West, 2006), 42.

^E.g., MacPherson v. Buick Motor Co., 217 N.Y. 382, 111 N.E. 1050 (N.Y. 1916) (discussed above, adjudicating the tort of negligence that existed in no statute, and expanding the law to cover parties that had never been addressed by statute); Hadley v Baxendale (1854) 9 Exch 341 (defining a new rule of contract law with no basis in statute); Marbury v. Madison, 137 5 U.S. 137 (1803) ("It is emphatically the province and duty of the judicial department to say what the law is."); Alexander Hamilton, THE FEDERALIST, Nos. 78 and 81 (J. Cooke ed. 1961), 521–530, 541–55 ("The interpretation of the laws is the proper and peculiar province of the courts. A constitution, is, in fact, and must be regarded by the judges, as a fundamental law. It therefore belongs to them to ascertain its meaning, as well as the meaning of any particular act proceeding from the legislative body."); see rule against perpetuities for a judicially created law originating in 1682 that governs the validity of trusts and future interests in real property, Rule in Shelley's Case for a rule created by judges in 1366 or before, and life estate and fee simple for rules of real property ownership that were judicially created in the late 1100s as the crown began to give law-making power to courts.

^E.g., George E. Woodbine (ed.), Samuel E. Thorne (transl.), Bracton on the Laws and Customs of England, Vol. I (Introduction) 46 (1968); Carl Güterbock, Bracton and his Relation to the Roman Law 35–38 (1866).

^Stephen P. Buhofer, Structuring the Law: The Common Law and the Roman Institutional System, Swiss Review of International and European Law (SZIER/RSDIE) 5/2007, 24.

^Peter Stein, Continental Influences on English Legal thought, 1600–1900, in Peter Stein, The Character and Influence of the Roman Civil Law 223 et seq. (1988).

^See generally Stephen P. Buhofer, Structuring the Law: The Common Law and the Roman Institutional System, Swiss Review of International and European Law (SZIER/RSDIE) 5/2007.

^E.g., Markman v. Westview Instruments, Inc., 517 U.S. 370, 376 (1996) ("[W]e [the U.S. Supreme Court] have understood that the right of trial by jury thus preserved is the right which existed under the English common law (connotation 3) when the Amendment was adopted. In keeping with our longstanding adherence to this 'historical test,' we ask, first, whether we are dealing with a cause of action that either was tried at law (connotation 3) at the time of the founding or is at least analogous to one that was. If the action in question belongs in the law category, we then ask whether the particular trial decision must fall to the jury in order to preserve the substance of the common-law right as it existed in 1791." citations and quotations omitted, holding that interpretation of the scope of a patent had no analogy in 1790, and is thus a question to be decided by a judge, not a jury)

^Note that the remainder of the "common law" discussed in the rest of the article remained intact; all that was abolished were the highly technical requirements for language of the paper provided by the plaintiff to the defendant to initiate a case.

^At least in the U.S., practicing lawyers tend to use "law professor" or "law review article" as a pejorative to describe a person or work that is insufficiently grounded in reality or practicality—every young lawyer is admonished repeatedly by senior lawyers not to write "law review articles," but instead to focus on the facts of the case and the practical effects of a given outcome.

^Swift v. Tyson, 41 U.S. 1 (1842). In Swift, the United States Supreme Court had held that federal courts hearing cases brought under their diversity jurisdiction (allowing them to hear cases between parties from different states) had to apply the statutory law of the states, but not the common law developed by state courts. Instead, the Supreme Court permitted the federal courts to make their own common law based on general principles of law. Erie v. Tompkins, 304 U.S. 64 (1938). Erie overruled Swift v. Tyson, and instead held that federal courts exercising diversity jurisdiction had to use all of the same substantive law as the courts of the states in which they were located. As the Erie Court put it, there is no "general federal common law", the key word here being general. This history is elaborated in federal common law.